[1] Deutsch Elektronen Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany
[2] Ctr Free Electron Laser Sci, Notkestr 85, D-22607 Hamburg, Germany
[3] Univ Hamburg, Dept Phys, Luruper Chaussee 149, D-22761 Hamburg, Germany
[4] ELI Beamlines Project, Inst Phys ASCR, Na Slovance 2, Prague 18221, Czech Republic
[5] Univ Hamburg, Ctr Free Electron Laser Sci, Luruper Chaussee 149, D-22761 Hamburg, Germany
[6] Univ Hamburg, Dept Phys, Luruper Chaussee 149, D-22761 Hamburg, Germany
[7] MIT, Dept Elect Engn & Comp Sci, Res Lab Elect, Cambridge, MA 02139 USA
[8] Inst Mol Sci, Laser Res Ctr, 38 Nishigonaka, Okazaki, Aichi 4448585, Japan